[phenixbb] special position

Hi all, I'm refining a structure with a phosphate ion on a 3-fold axis. I set occupancy manually to 0.33 and after refinement the ion has huge B-factor (close to 100) and there is a lot of positive electron density. I found somewhere that phenix recognizes special positions and there is not need to adjust occupancy manually. so I set it to 1 again and re-refined. This time my phosphate sits in a mixture of negative and positive density with B factor around 90 (for comparison Refmac refines it to ~20). Now I'm confused which procedure to follow. Karolina